.box750 {
    width: 750px;
    height: 750px;
    background-color: #EEEEEE;
  }
  .box640 {
    width: 640px;
    height: 640px;
    background-color: #CCCCCC;
  }
  .box320 {
    width: 320px;
    height: 320px;
    background-color: #AAAAAA;
  }
  .box480 {
    width: 480px;
    height: 480px;
    background-color: #AAAAAA;
  }
  .text {
    font-size: 50px;
  }
  .button{
    margin-top: 100px;
    width: 750px;
    height: 50px;
    background-color: black;
  }